What is the length of the cone?

6cm, 4cm, 2cm

The length of a cone typically refers to its height. However, with the dimensions you've provided, it seems that they are not enough to determine the length of a cone unless we know what those dimensions specifically represent. A cone generally has three different dimensions:

1. Radius (r) - The distance from the center of the base to the perimeter of the base.
2. Height (h) - The distance from the base to the tip of the cone, perpendicular to the base.
3. Slant height (l) - The distance from the tip of the cone to any point on the perimeter of the base along the surface.

If you provide the dimensions (height, radius, and slant height) correctly, only then can we calculate or understand the dimensions of the cone you are referring to.

For example, if the 6 cm and 4 cm dimensions represent the radius and height respectively, and the cone is a right circular cone (where the height is an altitude that connects the apex to the center of the circular base), you would typically not need a third measurement.

If however, the 6 cm is the slant height and the 4 cm is the radius of the base, the actual height (length) of the cone (h) can be found using the Pythagorean theorem for the right-angled triangle formed by the radius, slant height, and height:

h = √(l² - r²)
h = √(6² - 4²)
h = √(36 - 16)
h = √(20)
h = √(4*5)
h = 2√5 cm
h ≈ 4.47 cm

The height in this case would be about 4.47 cm.

Please provide additional information or clarify the dimensions to receive an accurate answer.